NEW YORK  Elizabeth Vargas and Bob Woodruff take the helm at ABC's World News Tuesday night, the first network evening news anchor team since CBS paired Dan Rather and Connie Chung in the '90s.

Elizabeth Vargas and Bob Woodruff take the place ofWorld News Tonight anchor Peter Jennings, who died in August.

By Kathy Willens, AP

The failed pairing of Rather and Chung followed ABC's attempt at dual anchors in the '70s, when the network paired Barbara Walters with Harry Reasoner.

Vargas says this latest venture bears no relation to earlier tries.

"This is not a cosmetic dual-anchor role," says Vargas, who anchors tonight's debut program from New York while Woodruff reports from Tehran. "This is two people doing two people's work. This isn't going to be us sitting on a set tossing back and forth and splitting 22 minutes of news.

On any given day, chances are one will report from the field while the other anchors from the studio.

Having two anchors "gives us an advantage: to report a lot of stories which don't get a lot of attention on network news and we didn't cover as aggressively as we could," World News producer Jon Banner says. " (Related story: Webcasts, blogs allow flexibility)

Vargas envisions herself or Woodruff reporting from cities such as Detroit on the sagging auto industry or in the aftermath of Hurricane Katrina as reconstruction continues or from Africa — "an underreported continent and story."

Vargas and Woodruff arrive at No. 2-rated World News as CBS News is courting NBC Today star Katie Couric for the CBS Evening News and a year after Brian Williams succeeded Tom Brokaw on NBC Nightly News.

Williams has kept Nightly News in first place with a big lead over World News: 9.9 million viewers compared with ABC's 8.6 million viewers. Meanwhile, ratings for CBS Evening News have surged under interim anchor Bob Schieffer with 7.8 million viewers.

As all news outlets try to build better mousetraps to attract viewers and readers, the heirs to Peter Jennings' news throne will co-write a daily online blog called The World Newser, produce a daily afternoon webcast called World News Now on ABCNews.com and give West Coast viewers, who usually must watch 3-hour-old newscasts, the only live network newscast of the day.

Exploding technology "means we have to take a really close look at how to do this, so that we can continue to do serious journalism in a way that many people will see it," Woodruff says. "If you had asked me 10 years ago if this is what the landscape would look like, I would have thought you were crazy."

NBC Nightly News producer John Rease says he doesn't feel threatened by the new World News. "The double anchor format has not worked," he says, adding that Williams' focus on Katrina helped solidify his bond with viewers. "They watched Brian, they liked what they saw, and they stuck with him."

Banner predicts evening-news viewers, who tend to stick with set habits, will be more willing to check out the competitors in the coming months. "We have a lot of work to do."